I'm trying to evaluate MatriX for our project, and the requirement is to connect to Openfire Server via SSO. I ran sample MiniClient sample, added UseSso=true to the "Connect" button handler - but it does not work. After xmppClient_OnBeforeSasl() nothing happens. I ran Wireshark trace as well, and there is no message coming from my application to the server. Log data is attached.

xmppClient does not return ANYTHING - it just "stops" right after BeforeSasl event... Server sends message with list of mechanisms to choose from - and xmppClient does not reply to this message..

after it gets the GSSAPI mechanism and UseSso it true it starts to initialize the GSSAPI mechanism with the kerberos Apis and send a token to the server. This is missing in your log so I assume there is a problem with SSPI.
Can you look if there are any exceptions in the degugger and subscribe to all MatriX Error events and the OnClose event?